Here is my code in multiplication:

.model small .stack 10h .data number db (?) digit db 0,0,'$' .code mov ax,@data mov ds,ax mov ax,3 int 10h mov ah,1 int 21h mov bl,al sub bl,30h mov ah,2 mov dl,10 int 21h mov dl,13 int 21h mov ah,1 int 21h mov number[0],al sub number[0],30h mov ch,0 mov cl,number[0] mov al,bl mov bl,0 balik: add bl,al loop balik mov ah,2 mov dl,10 int 21h mov dl,13 int 21h mov bh,0 mov cx,bx digit_0: cmp bl,0Ah jl digit_1 sub bl,0Ah inc digit[0] loop digit_0 digit_1: mov digit[1],bl add digit[1],30h add digit[0],30h mov ah,2 mov dl,digit[0] int 21h mov ah,2 mov dl,digit[1] int 21h mov ah,4ch int 21h end

That is for multiplication only. Can you gave me an idea on how should I convert my formula in multiplication in order that my calculator provide answer for addition, subtraction and multiplication..thanks in advance your attention is much appreciated.